#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<cstdio>

using namespace std;

int main()
{
    double wage, s, t;
    cin >> wage;
    if (wage > 0 && wage <= 2000)
        printf("Isento\n");
    else if (wage >= 2000.01 && wage <= 3000)
    {
        s = (wage - 2000) * 0.08;
        printf("R$ %.2lf\n", s);
    }
    else if (wage >= 3000.01 && wage <= 4500)
    {
        s = 1000 * 0.08 + (wage - 3000) * 0.18;
        printf("R$ %.2lf\n", s);
    }
    else
    {
        t = wage - 4500;
        s = 1000 * 0.08 + t * 0.28 + (wage - 3000 - t) * 0.18;
        printf("R$ %.2lf\n", s);
    }
    return 0;
}
